关于序列化：为什么Java在Exception和Throwable类中声明了serialVersionUID？

why Java declared serialVersionUID in Exception and Throwable class?

当我像下面一样创建一个自定义异常类时

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public class MyApppException extends Exception {

private String message = null;

public MyApppException() {
super();
}
public MyApppException(String message) {
super(message);
this.message = message;
}
public MyApppException(Throwable cause) {
super(cause);
}
}

编译器给了我下面的waning

The serializable class InsufficientBalanceException does not declare a static final serialVersionUID field of type long

从Java文档中，我理解了SerialValueUID的含义

The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. If the receiver has loaded a class for the object that has a different serialVersionUID than that of the corresponding sender's class, then deserialization will result in an InvalidClassException. A serializable class can declare its own serialVersionUID explicitly by declaring a field named"serialVersionUID" that must be static, final, and of type long:

但我不明白为什么Java声明异常的SerialValueUID和可抛出类？serialversionID在exception和throwable类中的用途是什么？真的需要吗？如果是，为什么？有人请澄清。

例外

1 2	public class Exception extends Throwable { static final long serialVersionUID = -3387516993124229948L;

可抛出

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public class Throwable implements Serializable {
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -3042686055658047285L;